*{
    margin: 0;
    padding: 0;
}
/*公共属性*/
.w{
    width: 1200px;
    margin: auto;
}
li{
    list-style: none;
}
a{
    text-decoration: none;
}
body{
    background-color: #f3f5f7;
}
.clearfix:before,.clearfix:after{
    content:"";
    display:table;
 }
 .clearfix:after{
   clear:both;
 }
 .clearfix{
    *zoom:1;
 }
 
/*头部模块*/
.header{
    height: 42px;
    /*注意此地方会层叠w里面的margin*/
    margin: 30px auto;
}
.logo{
    width: 198px;
    height: 46px;
    float:left;
}
/*导航栏模块*/
.nav{
    float:left;
    margin-left: 60px;
}
.nav ul li{
    float:left;
    margin: 0 15px;
}
.nav ul li a{
    display: block;
    height: 42px;
    padding: 0 10px;
    line-height: 42px;
    font-size:18px;
    color:#050505;
}
.nav ul li a:hover{
    border-bottom:2px solid #00a4ff;
    color:#00a4ff;
}
/*搜索模块*/
.search{
    width: 412px;
    height: 42px;
    float: left;
    margin-left: 70px;
    background-color:bisque;
}
.search input{
    float: left;
    width: 360px;
    height: 40px;
    border:1px solid #00a4ff;
    border-right:0;
    font-size: 14px;
    text-indent: 15px;
}
input::placeholder{
    color:#bfbfbf;
}
.search button{
    float: left;
    width: 50px;
    height: 42px;
    border:0; /*去掉边框*/
    background: url(img/btn.png)
}
/*用户模块*/
.user{
    float: left;
    line-height: 42px;
    margin-left: 30px;
    font-size: 14px;
    color:#666;
}
.user img{
    vertical-align: middle;
}
/*banner区域*/
.banner{
    height: 421px;
    background-color: #1c036c;
}
.banner .w{
    height: 421px;
    background: url(img/banner2_20190819_210028.png) no-repeat top center;
}
/*侧导航栏模块*/
.subnav{
    width: 190px;
    height: 421px;
    background:rgba(0,0,0,0.3);
    float: left;
}
.subnav ul li{
    height: 45px;
    line-height: 45px; /*居中对齐*/
    padding:0 20px; /*上下0 左右20px撑开*/
}
.subnav ul li a{
    font-size:14px;
    color:white;
}
.subnav ul li a span{ /*span左浮动*/
    float:right;
}
.subnav ul li a:hover{
    color:#00a4ff;
}
/*course课程模块*/
.course{
    width: 230px;
    height: 300px;
    background-color: #fff;
    float:right;  /*要浮动就一起浮动，上面的subnav也要加*/
    margin-top: 50px; /*浮动盒子不存在外边距合并*/
}
.course h2{
    height: 48px;
    background-color:#94cbe9;
    text-align: center;
    line-height: 48px;
    font-size:18px;
    color:white;
}
.content{
    padding: 0px 20px; /*上下0 左右20px*/
}
.content ul li{
    padding: 14px 0px; /*上下45px 左右0*/
    border-bottom: 1px solid #ccc;
}
.content ul li h4{
    font-size: 16px;
    color: #4e4e4e;
}

.content ul li p{
    font-size: 12px;
    color: #a5a5a5;
}
.content .more{
    display: block;
    height: 38px;
    border: 1px solid #00a4ff;
    text-align: center;
    line-height: 38px;
    margin-top: 5px;
    color:#00a4ff;
    font-size: 16px;
    font-weight: 700;
}
/*精品推荐模块*/
.good{
    height: 60px;
    line-height: 60px; /*行高会继承给3个孩子*/
    background-color: #fff;
    box-shadow: 0 2px 3px 3px rgba(0,0,0,0.1);
    margin-top: 10px;
}
.good h3{
    float:left;
    margin-left: 30px;
    font-size:16px;
    color:#00a4ff;
}
.good ul{
    float:left;
    margin-left: 30px;
}
.good ul li{
    float:left;
}
.good ul li a{
    padding: 0 30px;
    font-size:16px;
    color:black;
    border-left:1px solid #ccc;
}
.mod{
    float:right;
    margin-right:30px ;
    font-size:14px;
    color:#00a4ff;
}
/*精品大模块*/
.box{
    margin-top: 30px;
}
.box-hd{
    height: 45px;
}
.box-hd h3{
    float: left;
    font-size:20px;
    color:#494949;
}
.box-hd a{
    float: right;
    font-size:12px;
    color:#a5a5a5;
    margin-top: 10px;
    margin-right: 30px;
}
/*把li的父亲ul修改的足够宽就能装5个盒子不换行了*/

.box-bd ul{
    width: 1225px;
}

.box-bd ul li{
    float: left;
    width: 228px;
    height: 270px;
    background-color:#fff;
    margin-right: 15px;
    margin-bottom: 15px;
}
.box-bd ul li img{
    width: 100%; /*100%和父盒子一样宽*/
}
.box-bd ul li h4{
    margin: 20px 20px 20px 25px; /*上 右 下 左 边距*/
    font-size:14px;
    color:#050505;
    font-weight: 400;
}
.box-bd .info{
    margin: 0 20px 0 25px;
    font-size:12px;
    color:#999;
}
.box-bd .info span{
    color:#ff7c2d;
}
/*footer模块*/
/*此时footer盒子会跑到精品大模块下，即精品大模块父盒子高度为o，出现坍陷*/
/*此时给ul添加clearfix伪元素清除浮动即可*/
.footer{ 
    height: 415px;
}
.footer .w{ /*margin-top此时会出现上边距合并的情况！*/
    padding-top: 35px;;
}
.copyright{
    float: left;
}
.copyright p{
    font-size: 16px;
    color:#666;
    margin: 20px 0 15px 0;
}
.copyright .app{
    display: block;
    width: 118px;
    height: 33px;
    border:1px solid #00a4ff;
    text-align: center;
    line-height: 33px;
    font-size: 16px;
    color:#00a4ff;
}
.links{
    float: right;
}
.links dl{
    float:left;
    margin-left: 100px;
}
.links dl dt{
    font-size: 16px;
    color:#333;
    margin-bottom: 5px;
}
.links dl dd a{
    font-size: 12px;
    color:#333;
}